Substrate processing apparatuses are used in the manufacturing of electronic devices such as a semiconductor device. In substrate processing using the substrate processing apparatus, generally, a substrate is disposed within a chamber, and gas is supplied to the chamber. The flow rate of gas supplied to the chamber is controlled by a flow rate controller. The flow rate controller controls the output flow rate of gas in accordance with a set flow rate which is specified.
The flow rate of gas supplied to the chamber is an important factor having an influence on process results of substrate processing. Therefore, the output flow rate of the flow rate controller has to be calibrated in a timely manner. For that reason, it is necessary to determining the output flow rate of the flow rate controller. As a method of determining the output flow rate of the flow rate controller, a so-called build-up method is known. The build-up method is described in Japanese Patent Application Laid-Open Publication No. 2002-296096 and Japanese Patent No. 5538119.
In the build-up method, gas is output from the flow rate controller at an output flow rate in accordance with a set flow rate, and the gas is supplied to the internal space of a tank having a known volume. During the supply of gas into the tank, a measurement value of the pressure of the internal space is obtained by a pressure sensor. The rate of rise of the pressure of the internal space with respect to a time is determined by the obtained measurement value, and the output flow rate is determined using the rate of rise of the pressure. As the tank used in the build-up method, the chamber body of the substrate processing apparatus may be used, or a tank dedicated to the build-up method may be used.